Over the last decade or so, electronic devices responsible for establishing and maintaining wireless connectivity within a wireless network have increased in complexity. For instance, wireless electronic devices now support greater processing speeds and greater data rates. As a by-product of this increased complexity, radio communications techniques have evolved with the emergence of multiple-input and multiple-output (MIMO) radio architectures.
In general, MIMO involves the use of multiple antennas operating simultaneously as transmitters and/or receivers to improve communication performance. In comparison with other radio architectures, MIMO can offer significant increases in data throughput and link reliability. However, overall system throughput for a network still is adversely affected by wireless network (client) devices operating at low data transfer rates. More specifically, the wireless data transfer rate, sometimes referred to as “modulation and coding scheme (MCS) rate,” for client devices operating within a wireless network may greatly influence the overall system throughput because a client device operating at a lower MCS rate requires a greater amount of airtime to transmit a prescribed wireless packet than a client device operating at a higher MCS rate. This greater amount of requisite overall airtime translates into a lesser amount of data that can be transmitted over the wireless network.
The Institute of Electrical and Electronics Engineers (IEEE) standard entitled “Enhancements for Very High Throughput WLANs” (hereinafter “the IEEE 802.11ac standard”) introduces a beamforming scheme, which allows an access point (AP) to send data to a client device at a higher MCS rate by forming wireless “beam” signals toward the client device. This is accomplished by applying different amplitude and phase shifts between the antenna elements of the AP. According to the IEEE 802.11ac standard, beamforming may be conducted in accordance with single-user MIMO (SU-MIMO) or multi-user MIMO (MU-MIMO). For SU-MIMO, the beamforming involves the transmission of wireless signals from multiple antennas towards a single client device during a single time frame. For MU-MIMO, however, the beamforming involves altering the amplitude and phase shifts for transmitting wireless signals simultaneously to multiple client devices in a single time frame. To achieve the highest system throughput, both SU-MIMO and MU-MIMO communications need to be optimized.
Currently, some APs that are MU-MIMO enabled are configured to select, on a first-come, first-served basis, beamforming-capable client devices as they associate to the AP. However, the selection of client devices for beamforming on a first-come, first-served basis is inefficient as this selection scheme does not target those client devices that, upon achieving an increased MCS rate, would provide greater improvement to overall network throughput.